Immune monitoring is an important objective for the new one-dose trial (1DT) we plan to initiate later this year. Performance of assays designed to monitor immune response to single-dose vaccination are not fully understood (because levels seen after 1 dose are 4-5x lower than those observed after 2-3 doses). Also, given that the 1DT will include both the bivalent and the nonavalent vaccines, there is an interest in expanding testing beyond the two HPV types we have evaluated in the past. Evaluation of multiplex assays that incorporate all 9 HPV types included in the nonavalent vaccine is therefore of interest.